Most people can go through the majority of their life without ever appreciating the complicated structure of the knee that helps them walk. However, the knee remains a fragile mechanical structure that is readily susceptible to damage. While medical advances have made repairing the knee possible, repair of certain types of injuries results in other long term effects. To assist the reader, FIG. 1 is provided with a brief explanation of the components of the knee.
For the purposes of the present disclosure, and as illustrated, the knee may be composed of the quadriceps muscles 10, the femur 12, the articular cartilage 14, the lateral condyle 16, the posterior cruciate ligament 18, the anterior cruciate ligament 20, the lateral collateral ligament 22, the fibula 24, the tibia 26, the patellar tendon 28, the meniscus 30, the medial collateral ligament 32, the patella 34 (shown slightly displaced to the side—it normally rests in the center of the knee) and the quadriceps tendon 36. Of particular interest for the purposes of the present disclosure is the anterior cruciate ligament (ACL) 20 and what is done to repair the ACL 20.
ACL tears are common in athletes and are usually season ending injuries. The ACL 20 cannot heal—it must be surgically reconstructed. The reconstruction requires replacement tissue. The most common tissue used is a central slip of the patient's own patellar tendon 28. In practice, the patellar tendon 28 has proven to be generally effective, but the size of the graft that can be used is limited to the size of the patient's own patellar tendon 28. As a rule of thumb, only a third of the patellar tendon 28 may be harvested as a graft. Thus, a doctor will measure the width of the patellar tendon 28, divide by three, and take the middle third of the patellar tendon 28. Such harvested grafts are rarely more than 10 mm wide and may be smaller. Taking this tissue from a person's patellar tendon 28 also causes significant pain and discomfort in the post operative healing period, which may last up to a year, and up to twenty (20) percent of these patients are left with chronic anterior knee pain.
Some doctors recommend and use other graft sources, such as cadaver grafts, but cadaver grafts have a higher failure rate. Additionally, there is a non-zero chance of disease transmission or rejection by the patient's immune system. As a final drawback, cadaver grafts are usually quite expensive and may not be covered by some insurance companies.
Other doctors use hamstring tendons (e.g., the distal semitendinosus tendon) because the scar created during harvesting is relatively small and there is less pain during the rehabilitation, but again, the hamstring tendon has its own collection of disadvantages. The disadvantages include the fact that once the graft is taken, a patient's hamstring will never recover to its previous strength. Further, all hamstring reconstructions stretch and are looser than the original ACL 20. This loosening is particularly problematic in younger female athletes.
Another alternative graft source is the quadriceps tendon 36. The quadriceps tendon 36 is larger and stronger than either the patellar tendon 28 or the hamstring tendon. The quadriceps tendon 36 is likewise stiffer and less prone to stretching or plastic deformation. However, the qualities that make the quadriceps tendon 36 attractive also contribute to the difficulty in harvesting a graft from the quadriceps tendon 36. Existing surgical implements require a large incision up the longitudinal axis of the femur 12 on the front or ventral/anterior side of the thigh to cut down to the level of the quadriceps tendon 36, resulting in a large post operative scar. Additionally, the quadriceps tendon 36 has a consistency similar to the proverbial shoe leather, making it difficult to cut. However, an ACL 20 repaired with grafts from the quadriceps tendon 36 generally results in almost no anterior knee pain postoperatively over the short or long term and recovers quicker.
The present inventor's prior application, U.S. patent application Ser. No. 13/102,562, filed May 6, 2011 (which is hereby incorporated by reference in its entirety), provides a number of devices designed to create a graft from the quadriceps tendon 36 and discloses an element to make the initial cut on the quadriceps tendon 36 as well as a number of secondary cutting implements to trim the distal end of the graft. While these secondary cutting implements are adequate to perform their intended purpose, alternate devices may be more cost effective or have easier engineering realities.